Known as the "CAPS version 2" - a custom PC build designed by Chris Connaker of the Computer Audiophile website (www.computeraudiophile.com). Mine was built by Small Green Computer who have linked in with Chris Connaker (http://shop.smallgreencomputer.com/CAPS-20-CAPS.htm).

The PC, supposedly silent, emits a noise. The noise can be divided into 2 components; a constant "crackling" noise - this is quiet though audible with the ear near to the case. It seems to fluctuate if the PC is being used (e.g. scrolling down through a website or starting a program). Moving the mouse causes slight fluctuations in it. The second noise is the main problem - a constant high-pitched emission; this noise starts when the firewire port is connected to an external device.

The noise only starts when Windows boots up to the main screen (it is not there on the BIOS screens). The noise is definitely coming from the PC unit itself and not anything external to it such as the speakers. Given the effect the firewire cable has on the noise, I ran some tests:

1. All equipment off & connected - no noise2. Monitor on - no noise3. CAPS on - no noise initially, then system beep, then some noise when the Windows logo appears, then the continuous noise when the Windows welcome screen and then desktop appear4. Unplug monitor from CAPS - 1 second pause in noise, then resumes

5. Switch on DAC (connected to CAPS via 6pin-6pin firewire cable) - 1 second pause in noise, then resumes6. Switch off DAC - noise continues, no pause7. Unplug power from DAC - noise stops8. Plug in power to DAC - 4 second pause, then noise resumes

I tried disconnecting the SSD and booting up; I get a message saying "reboot and select proper boot device". There is no noise, though the noise only starts when the PC fires up into Windows anyway.

I looked into the firewire drivers on the PC. I tried a few different drivers that came with Windows, though they did not alter the sound. I then tried a driver from a third party (Unibrain - ubCore Firewire (Firewire 800 - IEEE 1394b) driver suite) and this significantly reduced the noise. However, when this driver was selected, the driver for my Weiss DAC2 seems to stop working:

The DAC2 is not recognised as long as the Unibrain firewire driver is being used. If I select the Windows legacy firewire driver and then disable the DAC2 driver, most of the sound goes away also (though not all of it). Of course I then cannot play music through the system as the DAC is disabled. I have tried a different firewire cable (4pin to 6pin) and used a 4pin to 6pin converter; this should cut the power leg of the cable. However, again no difference in sound.

When I run the Weiss DAC2 controller info program, it detects the OH 1394 Host Controller as: (1106) VIA Technologies, with chipset (3044) VT6307/6308. Finally, I tried connecting 2 firewire cables concurrently (there are 2 ports on both the DAC and the PC). This reduced the noise, though music will not play on the PC.

As you can see I have struggled with this for a while - any suggestions greatly appreciated!

It looks like it is the integrated speaker. The thing that "beeps" when a computer starts (well, or that it used to), and also warns when there's a problem with the hardware (like wrong RAM modules, or faulty videocard).

I wouldn't use something that would damage it, but you should be safe in making it more silent by closing the hole in some way. Desktop motherboards used to have a real speaker, and one could disconnect it if needed.